The Chargers had scored a touchdown in the final minute. Their margin now was 14-0. The offensive and defensive starters, collectively, ended the night on a high note and stood around their lockers, rehashing choice moments.

And then there was Ryan Mathews.

"The look on Ryan's face was of disgust," quarterback Philip Rivers said. "It was as if it was a terrible first half, which is good because it meant that much to him."

The Chargers scored a touchdown Saturday with seconds left in the second quarter, but it followed a Mathews fumble near the goal line. He attempted to scale the line of scrimmage — as he successfully did on a first-quarter plunge — but an opposing helmet ejected the ball loose and sent it flying across the field. The Cardinals recovered and ultimately fumbled it back on the same play in a lateral-gone-wrong, resulting in a Chargers touchdown during a 24-7 exhibition win.

To Mathews, all is not well that ends well.

"I didn't want to end on that," said Mathews, who took 14 carries for 57 yards. "It just eats me up; it really does. ... I can't do that, plain and simple. Everyone says, 'Oh well, it's preseason. It doesn't count.' But to me, it counts. I can't let my team down like that because when we get down there and they're calling my number, they've got to be able to rely on me."

The Chargers' faith in Mathews appears unshaken.

Aside from the fumble, for which Mathews and coach Mike McCoy agreed Cardinals defensive end Calais Campbell deserves some credit, the 25-year-old has shown good vision behind a more physical offensive line. He has 26 carries for 121 yards and a touchdown in three games.

The preseason fumble has his first. Mathews has lost seven of 12 career fumbles on 675 regular-season touches.

McCoy said Sunday "we were going to give it to him again the next play" should the Chargers have had another opportunity on the goal line.

"He's been getting after it," fullback Le'Ron McClain said. "Like I told him, he's like a different back this year. The way he put in his work this offseason, how he's performed in practice, it's easy for him out here on the field to be doing his thing. I know the fumble was big for him, but we were telling him in halftime, that's the joy of this game. You've got to move on to the next play."